Ribonucleoproteins (RNPs) are crucial elements in many biological processes and cell types. The polar granules of Drosophila melanogaster have long served as a model system for understanding the functions of RNPs. Polar granules are small, heterogeneous RNPs that specify the primordial germ cells in the fly. In this proposal, we will build upon the Drosophila knowledge using our wasp model system Nasonia vitripennis. The Nasonia equivalent of the polar granules is in the form of a large, spherical, solid RNP called the oosome. This is in contrast to the polar granules, which take the form of many small particles localized to the posterior pole of the embryo. The Nasonia oosome undergoes a dramatic migration within the posterior half of the embryo, a process which has not counterpart in Drosophila. Finally, the oosome is extruded in one very large bud that will divide and give rise to the pole cells. This is in strong contrast to pole cell formation in Drosophila, which is driven by the migration of nuclei to the posterior cortex, where individual cells form from small buds individually. The goal of this proposal is to understand the molecular and mechanistic properties of the oosome that are the basis for its morphological and functional differences from the polar granules. We will characterize the protein composition of the oosome, detail how translation is regulated within the oosome, and reveal how mRNAs and proteins are distributed throughout the oosome. We will then identify the interactions among proteins that may be important for the unique structure and function of the oosome. Finally, we will take in depth approaches to characterize the functions of novel components of the oosome. At the conclusion of this project, we will have a mechanistic understanding how the composition of the oosome and the interactions among the component molecules give rise to a novel form of RNP.